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  • Gleneagles Singapore

Thyroid Cancer

  • What is Thyroid Cancer?

    Thyroid cancer is cancer affecting the thyroid, a butterfly-shaped gland at the base of the neck that produces hormones that control your heart rate, blood pressure, body temperature and weight. It is the 8th most common cancer affecting women in Singapore.

    infographic showing a cancerous thyroid and a healthy thyroid

    Types of Thyroid Cancers

    Thyroid cancers are classed according to their cell types

    • Papillary thyroid cancer – This is the most common form that comes from the thyroid follicles.
    • Follicular thyroid cancer – Also from thyroid follicles, it may be difficult to tell apart from non-cancerous thyroid nodules.
    • Medullary thyroid cancer – This is a rare form of cancer that come from the cells located between thyroid follicles.
    • Anaplastic thyroid cancer – While rare, this form of cancer is aggressive and has a poorer recovery rate.
    • Thyroid lymphoma – A rare form of cancer, also known as non-Hodgkin lymphoma, that affects the white blood cells (lymphocytes).

    Causes

    Thyroid cancer may affect both the young and old. They are usually readily treatable and have very good cure rates, especially in younger patients.

    Mutations of certain genes have been known to cause papillary and follicular thyroid cancer. Unfortunately, it is not clear what causes these gene mutations, although over-exposure to radiation is a well-established cause. Certain inherited medical conditions like hereditary polyposis and type 2 multiple endocrine neoplasia (rare) are linked to thyroid cancers as well.

  • Signs & Symptoms

    lump in throat

    You may be at risk if you have a family history of thyroid cancer, or if you have previously been diagnosed with one of the above rare hereditary conditions. However, most cases are unpredictable in nature. They often present as a visible lump in the neck or are discovered as thyroid nodules (small swelling) on imaging done for other reasons. While most such lumps or nodules are non-cancerous, the possibility of thyroid cancer must be considered if they occur in the very young or the elderly, the nodule is growing quickly, there is unexplained weight loss, hoarseness of voice or presence of enlarged lymph nodes in the neck.

  • Diagnosis & Assessment

    anatomy of a cancerous thyroid gland

    You should see an endocrinologist (hormone specialist) for assessment. Every thyroid lump or nodule should be evaluated by ultrasound, which is affordable, safe and easily available. Ultrasound scans allow doctors to accurately measure the size of a nodule. Certain sonographic features may help to tell the differences between benign (non-cancerous) and cancerous nodules. Nodules that are small (below 1cm), well-defined or contain mostly fluid are likely benign. Hypoechoic nodules that appear tall with uneven borders, microcalcifications (small calcium build-up), hypervascularity (increased number of blood vessels) and more than 4cm with swollen lymph nodes are more likely to be cancerous. Thyroid function and thyroid antibodies should also be tested through blood tests as higher levels of thyroid stimulating hormone and antibodies are linked with a greater chance of cancer.

    Determining if a Thyroid Nodule is Cancerous

    All nodules more than 1cm should be tested to find out if it is benign or cancerous. This biopsy procedure may be easily done by an experienced radiologist or endocrinologist in the clinic. Using ultrasound to locate the nodule, a very thin needle is inserted into the nodule to draw out cells, which are then spread onto a slide and examined under a microscope. This procedure is known as fine needle aspiration (FNA). No anaesthesia is needed as the patient will only experience minor discomfort, very little bleeding and mild bruising at most. The whole procedure should be completed within a few minutes. The biopsy is classed into 6 categories (the Bethesda system) ranging from benign to cancerous. Should the result be uncertain, the FNA should be repeated. Nodules that are benign do not need to be removed, only checked yearly with an ultrasound and possibly an FNA to check for any changes. The possibility of a benign nodule becoming cancerous is very low.

  • Treatment & Care

    The patient should be ‘staged’ to work out the extent of the disease. Stage 1 is the earliest stage with the best outcome while stage 4 has the least favourable outcome. Special scans like radionuclide scans are used for staging. Age is the most important factor, as people below 45 years at the time of diagnosis usually mean the disease is in an early stage. Other deciding factors include the size of the tumour and the extent of spread.

    thyroid disease sign

    Surgical removal of the entire thyroid gland, including the surrounding lymph nodes in the neck, is the preferred option. This has the best chance for a successful cure, especially for people with early stage disease, and surgery may be the only treatment needed for this group of people. Removal of the entire thyroid gland also allows the endocrinologist to check for any possible return of the cancer by measuring the blood levels of thyroglobulin, which should not be found if the thyroid cancer has been removed. Surgery is also the treatment of choice for medullary thyroid cancer and thyroid lymphoma.

    After surgery, people with papillary or follicular thyroid cancer larger than 1cm should receive radioiodine treatment about 4 weeks later. This is usually done once and all the patient has to do is drink a small amount of solution with radioactive iodine in it. As only thyroid cells absorb iodine, this treatment will not harm other organ systems in the body. Radioiodine removes any remaining thyroid tissue that may still be present after surgery.

    After radioiodine treatment, a whole-body radionuclide scan is done to confirm that there is no remaining working thyroid tissue in the body, after which the patient will have to start on lifelong thyroid hormone replacement. Thyroxine replacement provides the thyroid hormones our body needs and prevents the thyroid cancer from returning. The endocrinologist will adjust the dosing appropriate for each patient. Patients with no sign of the disease returning will only need to have their serum thyroglobulin and thyroid function checked every 6 months.

    Patients with an advanced stage or a possible return of the disease may need extra doses of radioiodine. This treatment, however, is not useful in treating medullary thyroid cancer and thyroid lymphoma. Instead, such cases will need external beam radiation, chemotherapy and targeted therapy with tyrosine kinase inhibitors.

    Information kindly provided by Dr Richard Chen, consultant endocrinologist, Gleneagles Hospital.